Radiography in Modern Industry - Kodak

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combines with an interstitial silver ion. In the development process, the electrons are supplied bya chemical electron-donor and combine with the silver ions of the crystal lattice.The physical shape of the developed silver need have little relation to the shape of the silverhalide grain from which it was derived. Very often the metallic silver has a tangled, filamentaryform, the outer boundaries of which can extend far beyond the limits of the original silver halidegrain (See Figure 134). The mechanism by which these filaments are formed is still in doubtalthough it is probably associated with that by which filamentary silver can be produced byvacuum deposition of the silver atoms from the vapor phase onto suitable nuclei.Figure 134: Electron micrograph of a developed silver bromide grain.The discussion of development has thus far been limited to the action of the developing agentalone. However, a practical photographic developer solution consists of much more than a merewater solution of a developing agent. The function of the other common components of a practicaldeveloper are the following:An AlkaliThe activity of developing agents depends on the alkalinity of the solution. The alkali should alsohave a strong buffering action to counteract the liberation of hydrogen ions--that is, a tendencytoward acidity--that accompanies the development process. Common alkalis are sodiumhydroxide, sodium carbonate, and certain borates.A PreservativeThis is usually a sulfite. One of its chief functions is to protect the developing agent from oxidationby air. It destroys certain reaction products of the oxidation of the developing agent that tend tocatalyze the oxidation reaction. Sulfite also reacts with the reaction products of the developmentprocess itself, thus tending to maintain the development rate and to prevent staining of thephotographic layer.A RestrainerA bromide, usually potassium bromide, is a common restrainer or antifoggant. Bromide ionsdecrease the possible concentration of silver ions in solution (by the common-ion effect) and also,by being adsorbed to the surface of the silver bromide grain, protect unexposed grains from theaction of the developer. Both of these actions tend to reduce the formation of fog.Commercial developers often contain other materials in addition to those listed above. Anexample would be the hardeners usually used in developers for automatic processors.Radiography in Modern Industry 208
Chapter 19: ProtectionOne of the most important considerations in the x-ray or gamma-ray laboratory is the provisionand exercise of adequate safeguards for the personnel. Only the general principles of thenecessary protective precautions are discussed in the following.For details, obtain and carefully study the pertinent National Bureau of Standards Handbooks,publications from the National Council on Radiation Protection and Measurement, the AtomicEnergy Commission regulations, and the state and local codes. It is essential that newinstallations be constructed in compliance with the provisions of applicable codes and thatexisting installations be checked to make certain that they meet all requirements. It is desirable,and under some circumstances obligatory, to have a qualified radiation expert examine theradiation installation and protective measures. In addition, some state and local codes requirethat radiation-producing equipment be registered.Any of the body tissues may be injured by excessive exposure to x-rays or gamma rays--theblood, the lens of the eye, and some internal organs being particularly sensitive. Unless exposureto x-rays or gamma rays is kept at a minimum, the cumulative effect may cause injury to thebody, and it is essential that workers in the radiographic department be adequately protectedagainst radiation at all times. Furthermore, protective measures should be so arranged thatpersons in nearby areas are also safe. Precautions should be particularly observed whenradiography is done in the work areas of the shop rather than in a specially constructeddepartment.Protection Against X-RaysExposure may be caused by the direct beam from the x-ray tube target or by scattered radiationarising from objects in the direct beam. Therefore, while exposures are being made, operatorsshould always be protected by sufficient lead, or its equivalent, shielding them from the x-raybeam, the part being radiographed, and any other matter exposed to the x-rays.Protection can be provided in a number of ways, depending on the x-ray installation and the useto which it is put. Whenever possible, protective measures should be built in as permanentfeatures of the installation. Preferably, the x-ray generator and the work should be enclosed in aroom or cabinet, with the necessary protection incorporated in the walls.The common method is to locate the x-ray tube within a room completely lined with lead of asufficient thickness to provide adequate protection. All the controls are located outside the room.In the placing of equipment and the design of protective enclosures, keep certain principles inmind. Careful application of these principles adds to the safety of the personnel, and maydecrease cost.Both safety and economy benefit if the amount of radiation that must be absorbed in the outsidewall of the enclosure is kept to a minimum. To this end, the distance from the x-ray tube target toany occupied space should be as great as possible. Further, if the nature of the work permits, thedirect beam should never be pointed in the direction of occupied areas.Ideally, the lead housing around the x-ray tube should protect against all primary radiation exceptthe useful beam, although this is not always feasible in practice. The useful beam itself should belimited in cross section by the use of cones, diaphragms, or other devices.If there are parts of the x-ray room that, because of the design of the equipment, can never beexposed to direct radiation, certain economies in the installation of protective material are
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RadiographyinModernIndustry
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RadiographyinModernIndustryFOURTH E
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ContentsIntroduction...............
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Chapter 1: The Radiographic Process
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Intensifying ScreensX-ray and other
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makes it a very suitable material f
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Figure 6: Typical voltage waveforms
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Table I - Typical X-ray Machines an
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The wavelengths (or energies of rad
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Table III - Industrial Gamma-Ray So
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1. The source of light should be sm
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B and H in the Figure 13 show the e
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Figure 14: Geometric construction f
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Figure 17: Pinhole pictures of the
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The kilovoltage applied to the x-ra
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Figure 21: Schematic diagram of som
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kind of material radiographed, the
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instance, the kilovoltage may be fi
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The technique need not be limited t
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Chapter 5: Radiographic ScreensWhen
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Contact between the film and the le
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Figure 29: The number of electrons
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lead foil screens ran be retained w
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Figure 33: The sharpness of the rad
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Figure 34: Low density (right) is a
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such as a wall or floor, on the fil
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from this source. Since scatter als
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A filter reduces excessive subject
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Definite rules as to filter thickne
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0.010-inch front screen of value be
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Example: Suppose that with a given
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If the milliamperage remains consta
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espectively. In other words, a cons
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Any given exposure chart applies to
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Figure 46: Typical gamma-ray exposu
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where the slope of the characterist
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Figure 49: Characteristic curves of
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Figure 51: Characteristic curve of
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Nomogram MethodsIn Figure 54, the s
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Figure 56: Transparent overlay posi
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Figure 58: Overlay positioned so as
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The problem of radiographing a part
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Figure 62: System of lines drawn on
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Chapter 8: Radiographic Image Quali
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Film contrast refers to the slope (
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Hole Type PenetrametersThe common p
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of the same thickness as the specim
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Chapter 9: Industrial X-ray FilmsMo
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Figure 70 indicates the direction t
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the lead letters on a radiation-abs
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Therefore, protection requirements
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5. Avoid pressure damage caused by
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Paddles or plunger-type agitators a
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slow, and the development time reco
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ubbles make their way to the surfac
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When development is complete, the f
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soften considerably with prolonged
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Figure 77: The roller transport sys
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Rapid Access to Processed Radiograp
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Figure 78: Film-feeding procedures
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Chapter 11: Process ControlUsers of
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3. Age of the developer replenisher
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Figure 80: Control chart below for
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DiscussionDensitometric data and pr
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Figure 82: Plan of a manual x-ray p
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Figure 83: A schematic diagram of a
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loading-bench activities are carrie
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KODAK Quinone-Thiosulfate Intensifi
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Methylene-Blue MethodTwo variations
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KODAK Hypo Test Solution HT-2Avoird
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In summary, use of the test papers
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narrow angle would be very thick, e
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When radiation passes through a spe
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Figure 89: Demonstration of the eff
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Figure 90: The amount of gamma radi
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The radiograph exposed in the right
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To illustrate, let us assume that t
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Figure 95: High-speed x-ray picture
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Page 159 and 160: Duplicating RadiographsSimultaneous
Page 161 and 162: Sometimes, as when sets of referenc
Page 163 and 164: PhotofluorographyIn photofluorograp
Page 165 and 166: discontinuities or of segregation i
Page 167 and 168: from the camera or by reaching down
Page 169 and 170: Figure 106: Schematic diagram of th
Page 171 and 172: valuable technique, for instance, i
Page 173 and 174: The position of the spots is determ
Page 175 and 176: Powder Diffraction File, Internatio
Page 177 and 178: Processing TechniquesRadiographs on
Page 179 and 180: Since this formula applies only to
Page 181 and 182: such that it does not distort the i
Page 183 and 184: Figure 113: A: Representation of a
Page 185 and 186: Figure 115: Characteristic curve of
Page 187 and 188: film fairly well. If high densities
Page 189 and 190: Density = 1.5 Density = 2.5Film Rel
Page 191 and 192: In most industrial radiography, the
Page 193 and 194: e noted here. Although the average
Page 195 and 196: Chapter 17: Film Graininess; Signal
Page 197 and 198: The ratio of signal to noise has a
Page 199 and 200: Chapter 18: The Photographic Latent
Page 201 and 202: Thus, the change that makes an expo
Page 203 and 204: Figure 130: Stages in the developme
Page 205 and 206: electrons by successive Compton int
Page 207: Development is essentially a chemic
Page 211 and 212: duct is brought into the x-ray room
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